There is a conventional rotary compressor as disclosed in, for example, Japanese Patent Application Laid-Open Gazette No. 6-147164, the rotary compressor comprising: a cylinder in which a cylinder room is formed; side housings respectively disposed on top and bottom surfaces of the cylinder to close the cylinder room; an annular piston which is disposed in the cylinder room and is rotatably fit at its inner periphery into a decentered shaft part of a driving shaft; a blade which is formed integrally with the piston and protrudes from the outer periphery of the piston to divide the cylinder room into a low pressure room communicating with an inlet port and a high pressure room communicating with a discharge port; and a swing bush swingably disposed in a bush hole which is formed in the cylinder and faces the cylinder room, the swing bush supporting the blade so that the blade is swingable and movable forward and backward.
When the driving shaft is rotated, the piston is revolved around the driving shaft in the cylinder room with supported by the swing bush as a supporting point through the blade, so that a fluid such as a refrigerant gas sucked from the inlet port at each revolution of the piston is compressed and discharged from the discharge port.
In the above-mentioned rotary compressor, the inlet and discharge ports are both formed in the cylinder and are open toward the cylinder room in a direction orthogonal to an axial direction of the driving shaft.
-Problem to be Solved-
In the above-mentioned rotary compressor, since the bush hole is formed in the cylinder, it is necessary to form the discharge port at a distance from the bush hole in order to prevent decrease in strength of the cylinder.
However, when the discharge port is formed at a distance from the bush hole, the discharge port is located apart from a position that the piston completes its one revolution. As a result, invalid power is produced during the time from the closing of the discharge valve to the completion of one revolution of the piston. This reduces efficiency of the compressor.
In view of the foregoing problem, the present invention has been made. An object of the present invention is to dispose a discharge port as close as possible to a position that the piston completes its one revolution so as to delay a revolution angle that a discharge valve completes the discharge of a fluid and reduce invalid power of the piston, thereby obtaining high compression efficiency.